917 research outputs found
Generation of Total Angular Momentum Eigenstates in Remote Qubits
We propose a scheme enabling the universal coupling of angular momentum of
remote noninteracting qubits using linear optical tools only. Our system
consists of single-photon emitters in a -configuration that are
entangled among their long-lived ground-state qubits through suitably designed
measurements of the emitted photons. In this manner, we present an
experimentally feasible algorithm that is able to generate any of the
symmetric and nonsymmetric total angular momentum eigenstates spanning the
Hilbert space of the -qubit compound.Comment: 5 pages, 4 figures, improved presentation. Accepted in Physical
Review
A versatile source of polarization-entangled photons
We propose a method for the generation of a large variety of entangled
states, encoded in the polarization degrees of freedom of N photons, within the
same experimental setup. Starting with uncorrelated photons, emitted from N
arbitrary single photon sources, and using linear optical tools only, we
demonstrate the creation of all symmetric states, e.g., GHZ- and W-states, as
well as all symmetric and non-symmetric total angular momentum eigenstates of
the N qubit compound.Comment: 4 pages, 3 figure
Mid-Infrared Optical Frequency Combs based on Difference Frequency Generation for Molecular Spectroscopy
Mid-infrared femtosecond optical frequency combs were produced by difference
frequency generation of the spectral components of a near-infrared comb in a
3-mm-long MgO:PPLN crystal. We observe strong pump depletion and 9.3 dB
parametric gain in the 1.5 \mu m signal, which yields powers above 500 mW (3
\mu W/mode) in the idler with spectra covering 2.8 \mu m to 3.5 \mu m.
Potential for broadband, high-resolution molecular spectroscopy is demonstrated
by absorption spectra and interferograms obtained by heterodyning two combs.Comment: 11 pages, 8 figure
Takagi-Taupin Description of X-ray Dynamical Diffraction from Diffractive Optics with Large Numerical Aperture
We present a formalism of x-ray dynamical diffraction from volume diffractive
optics with large numerical aperture and high aspect ratio, in an analogy to
the Takagi-Taupin equations for strained single crystals. We derive a set of
basic equations for dynamical diffraction from volume diffractive optics, which
enable us to study the focusing property of these optics with various grating
profiles. We study volume diffractive optics that satisfy the Bragg condition
to various degrees, namely flat, tilted and wedged geometries, and derive the
curved geometries required for ultimate focusing. We show that the curved
geometries satisfy the Bragg condition everywhere and phase requirement for
point focusing, and effectively focus hard x-rays to a scale close to the
wavelength.Comment: 18 pages, 12 figure
Versatile silicon-waveguide supercontinuum for coherent mid-infrared spectroscopy
Infrared spectroscopy is a powerful tool for basic and applied science. The
molecular spectral fingerprints in the 3 um to 20 um region provide a means to
uniquely identify molecular structure for fundamental spectroscopy, atmospheric
chemistry, trace and hazardous gas detection, and biological microscopy. Driven
by such applications, the development of low-noise, coherent laser sources with
broad, tunable coverage is a topic of great interest. Laser frequency combs
possess a unique combination of precisely defined spectral lines and broad
bandwidth that can enable the above-mentioned applications. Here, we leverage
robust fabrication and geometrical dispersion engineering of silicon
nanophotonic waveguides for coherent frequency comb generation spanning 70 THz
in the mid-infrared (2.5 um to 6.2 um). Precise waveguide fabrication provides
significant spectral broadening and engineered spectra targeted at specific
mid-infrared bands. We use this coherent light source for dual-comb
spectroscopy at 5 um.Comment: 26 pages, 5 figure
Peripheral Sensory Neuropathy Associates With Micro- or Macroangiopathy: Results from a population-based study of type 2 diabetic patients in Sweden
OBJECTIVE—To assess associations between peripheral sensory neuropathy (PSN) and other diabetes-related complications
Changes of the phagosomal elemental concentrations by Mycobacterium tuberculosis Mramp
Pathogenic mycobacteria survive within phagosomes which are thought to represent a nutrient-restricted environment. Divalent cation transporters of the Nramp family in phagosomes and mycobacteria (Mramp) may compete for metals that are crucial for bacterial survival. The elemental concentrations in phagosomes of macrophages infected with wild-type Mycobacterium tuberculosis (M. tuberculosis strain H37Rv) and a M. tuberculosis Mramp knockout mutant (Mramp-KO), derived from a clinical isolate isogenic to the strain MT103, were compared. Time points of 1 and 24 h after infection of mouse peritoneal macrophages (bcgS) were compared in both cases. Increased concentrations of P, Ni and Zn and reduced Cl concentration in Mramp-KO after 1 h of infection were observed, compared to M. tuberculosis vacuoles. After 24 h of infection, significant differences in the P, Cl and Zn concentrations were still present. The Mramp-KO phagosome showed a significant increase of P, Ca, Mn, Fe and Zn concentrations between 1 and 24 h after infection, while the concentrations of K and Ni decreased. In the M. tuberculosis vacuole, the Fe concentration showed a similar increase, while the Cl concentration decreased. The fact that the concentration of several divalent cations increased in the Mramp-KO strain suggests that Mramp may have no impact on the import of these divalent cations into the mycobacterium, but may function as a cation efflux pump. The concordant increase of Fe concentrations within M. tuberculosis, as well as within the Mramp-KO vacuoles, implies that Mramp, in contrast to siderophores, might not be important for the attraction of Fe and its retention in phagosomes of unstimulated macrophages
- …